1. Field of the Invention
The present invention relates to an X-ray mask used in a semiconductor exposure device using an X-ray source, a method of manufacturing the X-ray mask and a semiconductor device manufacturing method using the X-ray mask.
2. Description of the Related Art
An example of generally known X-ray masks used in X-ray exposure devices is described below.
As shown in FIG. 10, an X-ray mask substrate 50 is joined to a mask frame 54. The X-ray mask substrate is produced by depositing an inorganic film 52 of SiN or the like on the surface of a silicon substrate 51, removing a portion corresponding to a permeable film portion 52a by dry etching, and removing a portion of the silicon substrate 51 which corresponds to the permeable film portion 52a by wet etching. A pattern 55 made of an X-ray absorber such as Ta, Au or the like is provided on the permeable film portion 52a in correspondence with a predetermined shape to be transferred to a wafer (not shown).
When exposure is performed by an exposure device to which the X-mask is fitted, the surface of the X-mask in which the pattern is formed is opposed to a wafer at a distance of about 30 .mu.m. In this state, a portion of the wafer is exposed to light. When another portion of the wafer is then to be exposed to light, the distance between the X-ray mask and the wafer is increased to about 200 .mu.m, and the X-ray mask is then moved to a position corresponding to the other portion. The distance between the X-ray mask and the wafer is then returned to about 30 .mu.m, and the other portion is exposed.
The step-and-repeat operation is successively repeated to expose the wafer.
However, during exposure using the above conventional X-ray mask, when the X-ray mask once separated from the wafer is brought back close to it, if the X-ray mask is rapidly moved, the gas present in the gap between the X-ray mask and the wafer cannot easily escape from the gap and is thus compressed as the X-ray mask is brought close to the wafer. The pressure of the gas between the X-ray mask and the wafer is thus increased in correspondence with the speed of movement of the X-ray mask toward the wafer. This increase in the pressure causes a danger of breaking or damaging the permeable film portion serving as a permeable support film. There is also the problem that if the speed of movement of the X-ray mask toward the wafer is decreased for preventing the breakage of the permeable film portion, the productivity of the exposure device is decreased.